The present invention relates to a shield case for an electronic equipment such as a receiver, an electronic tuner, an amplifier and so on, which is composed of a plurality of thin metal panels assembled to one another into a box-like shape, and in an interior of which wiring boards carrying thereon electronic elements, integrated circuit elements, etc., electronic components and so on are disposed.
Generally, in the electronic equipment such as the receiver, the electronic tuner, the amplifier and so on, the wiring boards carrying thereon the electronic elements, the integrated circuit elements, etc., the electronic components and so on have been disposed in a shield case which has been constructed by assembling thin metal panels. The electronic equipment has been so constructed that effects of electromagnetic noises from outside and occurring inside may be restrained, and mechanical protection can be attained by the shield case.
The related shield case is composed of constituent panels such as a front panel, side panels, a ceiling panel, a bottom panel or a back panel which are assembled to one another into a box-like shape. In the related shield case, the constituent panels have been assembled in such a manner that against a main face of one of the members is abutted a side end portion of a mating member, and then assembled with a caulking structure.
In other words, in the related shield case 100, as shown in FIGS. 5 and 6 for example, a side end portion 102a of a side panel 102 is abutted against an inner face 101a of a front panel 101, and assembled by means of a connecting structure which will be described later in detail. After the constituent panels have been assembled, the shield case 100 is attached to a mount panel 111 by means of fitting screws 111.
The front panel 101 is formed with a plurality of caulking holes 103 each having a rectangular shape along its side end portions 101b. The front panel 101 is also formed with a plurality of fitting holes 104 into which the fitting screws 111 are adapted to be screwed.
The side panel 102 is provided at the side end portion 102a with caulking pieces 105 in a shape of a tongue-like projection corresponding to the caulking holes 103. Each of the caulking pieces 105 is continuously formed from a base portion which is formed by cutting away a pair of slits 106 respectively opening in the side end portion 102a, and a distal end portion 105a is formed substantially in a shape of a hook. A sectional dimension of the distal end portion 105a of the caulking piece 105 is rather smaller than the size of the caulking hole 103.
In the shield case 100, the side end portion 102a of the side panel 102 is abutted against to the inner face 101a of the front panel 101, and the caulking pieces 105 are respectively engaged in the associated caulking holes 103. In the shield case 100, the distal end portion 105a of the caulking piece 105 which is projected from a front face 101c of the front panel 101 is bent downward by caulking treatment. In the shield case 100, as shown in FIG. 6, the bent distal end portion 105a of the caulking piece 105 is locked at an edge of the caulking hole 103 whereby the side panel 102 is assembled to the front panel 101. By assembling all the constituent panels by means of a similar structure, the shield case 100 is constructed in a box-like shape as a whole.
In the shield case 100, the above described constituent panels are assembled to one another without employing any fastening means such as screws, welding or deposition. The shield case 100 is attached to the mount panel 110 by means of the fitting screws 111 in a state where the circuit boards equipped with the integrated circuit elements or so, the electronic components or the like have been disposed inside and a ceiling panel (not shown) has been assembled thereto.
In the related shield case 100, the distal end portion 105a of the caulking piece 105 is projected from the front face 101c of the front panel 101 as described above. In a state where the shield case 100 has been attached to the mount panel 110, the distal end portion 105a is abutted against the inner face 110a of the mount panel 110, as shown in FIG. 6. Accordingly, when the shield case 100 is attached to the mount panel 110, there is formed a gap t corresponding to a thickness of the distal end portion 105a of the caulking piece 105 between the front face 101c of the front panel 101 and the inner face 110a of the mount panel 110 as shown in the same drawing.
The front panel 101 and the side panel 102 of the shield case 100 are formed of the thin metal panels as described above, and are rather weak in mechanical strength in a direction of their thickness. Therefore, since there is provided the gap, the front panel 101 is likely to be deformed or flexed in a direction of its thickness in case where the shield case 100 has become heavy with a number of the circuit boards, the electronic components an so on disposed therein or an impactive force is applied to the shield case. For this reason, there has been a problem in the shield case 100 that sufficient shielding performance cannot be attained, because gaps may occur between the front panel 101 and the side panel 102, or between the front panel 101 and the ceiling panel or the bottom panel. There has been a further problem that the shield case 100 cannot be firmly attached to the mount panel 110.
It has been considered that the front panel 101 of the shield case 100 may be formed of a thick metal panel. However, this will lead to a problem that an overall cost will be increased because cost for material, changes in manufacturing steps of the components and in control steps, etc. are required. There will be a further problem that the shield case 100 may become larger in size and heavier in weight by employing such a countermeasure.
In view of the above, it is an object of the present invention to provide a shield case for an electronic equipment in which mechanical strength of a front panel is enhanced to maintain reliable shielding performance.
In order to achieve the above object, according to the present invention, there is provided a shield case accommodating therein an electronic equipment and mounted on a mount panel, comprising:
a first panel, an outer face of which is brought into an intimate contact with the mount panel to fix the shield case thereon;
a calking piece provided with a first arm portion extended from a side edge portion of the first panel toward inside of the shield case, and second arm portion connected to the first arm portion so as to extend substantially parallel with the first panel toward outside of the shield casing; and
a second panel, a side edge of which is abutted on an inner face of the first panel, the second panel formed with an calking hole through which the second arm portion of the calking piece is inserted.
In this configuration, the second panel is assembled to the first panel by applying caulking treatment to the distal end portion of the caulking piece which is projected from the caulking hole. The first panel is attached to the mount panel, and joined thereto to be fixed by fitting screws or the like. Since the first panel is joined to the mount panel in substantially intimate contact along its whole surface, mechanical strength in a direction of its thickness will be maintained, and deformation of the first panel can be restrained even when a large load, an impact or so is applied thereto, whereby the shielding performance can be maintained.